Mission M01: The Robot needs to send Payload rockets (carts) rolling down the Space Travel Ramp. The first cart is pre-set and ready to go, but the Robot needs to load the other two from Base.
We have two skiers in our team. They both immediately recognized the type of motion and engine required. If you look up a video on how to ride a ski lift , you will agree with them.
It was more difficult to find the Lego pieces needed to build such a wheel. Luckily LEGO had a set that used them for a completely different purpose, the Technic Bucket Wheel Excavator 42055. Even the color matched.
That helped identify the pieces needed: Technic 11×11 curved rack gear (No: 24121). However, the set is expensive and it was not produced anymore, but BrickLink.com had spare pieces and we could also find the pdf.
We wanted to simply turn the wheel with a large motor, not with a complex gear system as the excavator did, so we used 20T double bevel gears to roll on the rack, a 60T turntable and we built a simple frame to make the wheel stiffer.
Initially we used only one wheel. Rarely, one of the gears slipped, so we ended by doubling the wheel.
First Lego League Robotics 
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